1. Technical Field
The present disclosure relates to cathode active materials used in rechargeable lithium ion batteries, and particularly to a cathode composite material used in a rechargeable lithium ion battery.
2. Description of Related Art
Lithium ion batteries can experience capacity loss during charging and discharging cycles and a poor cycling life due to the capacity loss. One reason for the capacity loss during the cycling is an un-reversible change of an intrinsic structure of a cathode active material that occurs during cycling. Another reason for the capacity loss during the cycling is a cathode active material loss caused by a reaction between the cathode active material and the organic solvent that occurs when the cathode active material is in a lithium ion deintercalation state and thus has a high oxidability. Therefore, how to improve the stability of the cathode active material during cycling of the battery and decrease unwanted reactions in the battery is crucial in improving the cycling life of the lithium ion battery.
A common method to improve the conductive properties of cathode active materials of lithium batteries is to treat the surface of the materials. For example, compared to untreated LiFePO4, the carbon coated LiFePO4 particles have improved conductivity. However, the stability improving problem during the cycling of the lithium ion battery has not been properly solved.
What is needed, therefore, is to provide a cathode composite material having a relatively good cycling stability and a lithium ion battery using the same.